A full-length and replication-competent proviral clone of SIVAGM from tantalus monkeys

Abstract African green monkeys (AGM) are classified into four distinct species (commonly termed vervet, grivet, sabaeus, and tantalus monkeys), all of which are known to be infected with simian immunodeficiency virus (SIV AGM ) in the wild. Sequence analysis of partial gag and env regions has indicated that each of the four species harbors a phylogenetically distinct SIV AGM subtype. This species-specific diversity suggests that African green monkeys have been infected with SIV AGM for an extended period of time, possibly even before their speciation from a common ancestor. However, our understanding of the evolutionary history of this group of viruses is still incomplete, in part because sequence information for most isolates is limited to small subgenomic regions. There are only six SIV AGM proviruses which have been sequenced in their entirety, and these represent only three of the four SIV AGM lineages (i.e., SIV AGM gri, SIV AGM ver, and SIV AGM sab). In this paper, we have generated the first full-length proviral clone for SIV AGM infecting tantalus monkeys (SIV AGM tan). Lambda phage techniques were employed to clone this provirus (TAN) as a single genomic unit from productively infected Molt 4 (clone 8) cells, and sequence analysis confirmed the integrity of all major open reading frames, except vpr which contained an in-frame stop codon. The proviral clone was also biologically active since transfection yielded replication-competent virions. Amino acid sequence comparisons of all major viral proteins indicated that TAN was roughly equidistant from previously characterized sabaeus, grivet, and vervet strains, thus confirming that it represents a fourth independent SIV AGM lineage. Given the need for well-characterized reference reagents, this full-length tantalus provirus should facilitate future studies of SIV AGM molecular biology and evolution.